For a method of checking the health condition of a person being examined, such methods as medical check or examination by means of an endoscope are widely known. Moreover, an examination method that uses a capsule type medical device wherein an examination instrument formed in capsule shape is introduced inside the living body to conduct easy physical condition examination is known (for example, refer Japanese Unexamined Patent Application, First Publication No. 2003-135388). Various types of capsule medical devices similar to the aforementioned device are available, one of which is an electric propelling type device wherein local electric stimulation is given to body tissue through electrodes and contraction of the body tissue is utilized to move inside the living body (for example, refer to PCT International Publication No. WO 01/08548, and U.S. Patent Application Publication No. 2003/0125788).
Normally, a capsule medical device, when introduced to the living body, moves naturally inside the digestive tube through peristaltic movement of a luminal organ such as the small intestine. However, this electric propelling type capsule medical device promotes forward movement or movement in a reverse direction by giving electric stimulation locally to body tissue such as a luminal organ, inducing contraction motion (inducing compulsory peristalsis or local muscle contraction) different from peristaltic movement which is natural (autonomic) to the body tissue. This allows speedy reaching to position to be observed, or detailed observation at one location. Hence, an effective observation is achieved.
In the capsule type medical device disclosed in PCT International Publication No. WO 01/08548, electrodes are provided in an expandable balloon in order to cope with changes in the diameter of a luminal organ. However, in this device, it is necessary to expand the balloon by blowing a fluid such as air into the capsule type medical device from outside of the living body using a tube or the like. Hence, a relatively large tube is needed to blow the fluid into the balloon, making it difficult to deploy the device inside the living body. Moreover, often the person examined feels uneasy or uncomfortable. Furthermore, if the tube gets caught inside the luminal organ, stable propelling of the capsule medical device may be interrupted. Moreover, in the capsule type medical device disclosed in PCT International Publication No. WO 01/08548, a detailed description concerning the structure and mechanisms behind the power supply to the electrode are not given, and it is clear that a further improvement is needed.
In the capsule type medical device disclosed in the specification of U.S. Patent Application Publication 2003/0125788, electrodes for electric stimulation are attached to swingable flap, and by opening the flap with expandable balloon, the problem of change in the diameter of the luminal organ is handled. However, similar to the model disclosed in Japanese Unexamined Patent Application, First Publication No. 2003-135388, a tube is needed to blow air or the like to expand the balloon. In addition, even when the flap is opened to the maximum size, the distance between the electrodes is about the same as the diameter of the capsule, hence, a problem occurs in that the device clearly cannot be used for luminal organs with a diameter larger than that of the capsule.